Serious refactoring of object model

Mostly this is a simplification of the object model, removing classes
and methods that are currently only called in one other place, and using
the Python property pattern.  The intent is to make the code easier to
maintain and more clear for new developers, at some cost to
extensibility.  Also, the pattern/lookup functionality is removed for
the time being (further reducing complexity) in favor of a simpler
cloudlet format for version 1.
Merge branch 'master' of github.com:huit/nepho into refactor/object-model
fix variable
Payload and bootstrap scripts

Upload payload directory to an obfuscated S3 bucket, generate a URL
with a 1 hour expiration time, pass URL to CF template for download.
Run bootstrap scripts from CF if they are present.

Need to implement S3 lifecycle to delete object and bucket afterwards,
and possibly better lock down security to only the generated URL?
Provider fixes

Vagrant spins up in the resource dir without templating (for now), AWS
uses a shared (user-specific) private bucket for payloads, with the
expiring URL for instance access
Fixing Vagrant stack commands
Merge branch 'master' of github.com:huit/nepho into refactor/object-model
Merge pull request #156 from agperson/refactor/object-model

Serious object model refactoring and simplification, working AWS payload/bootstrap